1. Field of the Invention
The present invention relates generally to a lens drive mechanism of an auto-focusing camera, and more particularly to a drive mechanism of an auto-focusing camera with a built-in lens.
2. Description of Related Art
Conventionally, an auto-focus structure is used for controlling the telescopic movement of a lens of the camera. The auto-focus structure is used to automatically produce high-quality images with minimum user's effort, and as such is an important part of a modern digital camera.
The auto-focus structure of the camera focuses on an object by analyzing the image on an image sensor which is controlled by a central processing unit (CPU) installed inside the digital camera. The auto-focus structure operates by moving the lens back and forth around its original (static) position. As the lens moves, the CPU compares the image from the lens with the image in the image sensor. Finally, as the lens moves to the position where the image is fully in focus, the lens then stops in that position. In this case, the lens has to be continuously driven back and forth by a motor. Generally the motor is column-shaped, including a stator having a stator core and coils wound around the stator core and a permanent magnet mounted around the lens. During operation of the motor, a current is applied to the coils to establish an alternating magnetic field. The magnetic field of the permanent magnet interacts with the alternating magnetic field of the stator to drive the lens to move. At the moment when the CPU detects a focused image as the lens moves back and forth, a stop signal is simultaneously sent to the motor. Therefore, the lens stops at the best focal position (static position).
A pin holder is for connecting the coils with a power source to provide the current to the coils to drive the motor into operation. The pin holder is formed on a side of the motor. A plurality of pins are received in the pin holder and connect with ends of the coils to electrically connect the ends of the coils to the power source. However, the pins are formed on a cylindrical housing of the motor which constitutes the column shape of the motor, and a circuit board for applying currents to the coils is usually arranged under the motor. Wiring is needed to electrically connect the ends of the coils to the circuit board, which causes production and assembly of the motor to be costly and awkward.